Macromolecular Chemistry and Physics最新文献

In addition to traditional rubber applications, 1,4-cis-polyisoprene (cis-PI) has been utilized in wearable electronics. While synthetic PI typically exhibits lower durability compared to natural rubber (NR), high-molecular-weight cis-PI compensates by offering improved mechanical properties and chemical resistance. The group proposes using a commercial cis-PI with high molecular weight of 250 000 g mol⁻¹ (PI_250K-C) grafted onto modified nanoparticle structures including silicon dioxide (mSiO₂), rutile titanium dioxide (mRTiO₂), and anatase titanium dioxide (mATiO₂) as an insulator in organic field effect transistors (OFETs) due to its naturally low dielectric constant. The nanoparticles are pretreated with a coupling agent to improve adhesion and prevent aggregation. Rubber composite films, designated X%-mY-PI_250K-C (where X = 10, 20, 30% and Y = mSiO₂, mRTiO₂, mATiO₂), are fabricated using sulfur vulcanization. The modified films demonstrate excellent mechanical stress (1.15 ± 0.1 MPa) and elasticity, enduring 50 loading–unloading cycles without residual strain. In contrast, rubber composites produced from simple blending show half the mechanical stress at 0.7 ± 0.3 MPa, which is attributed to nanoparticle agglomeration observed in SEM and EDX results. Additionally, mRTiO₂ nanoparticles significantly increase the dielectric constant of PI_250K-C from 2.12 to 12.93, enhancing electrical performance for TFT applications. This study underscores the effectiveness of the “grafting to” approach for producing robust rubber composites, highlighting the importance of nanoparticle selection and fabrication precision for stretchable organic electronics.

The effect of chain dispersity on the relative stability of Frank–Kasper (FK) phases self-assembled from diblock copolymers (DBCPs) is studied using self-consistent field theory applied to DBCPs with one disperse block obeying the Poisson or Schulz–Zimm distributions. The results demonstrate that the chain dispersity enhances the relative stability of the FK phases. For DBCPs with small conformational asymmetry, the FK $�\sigma$ phase can be stabilized by dispersity and the stability window of the FK phases widens with the increase of dispersity. For DBCPs with large conformational asymmetry, the Laves C14 and C15 phases, which are metastable in monodisperse DBCPs, can be stabilized by dispersity. An analysis of the spatial organization of polymers reveals that the enhanced stability of the FK phases originated from intra- and inter-domain segregation of chains with different lengths.

As functional composite materials rapidly develop, the insufficient thermal conductivity of polymer materials to meet application requirements is becoming increasingly apparent. In this work, electrospinning is employed to prepare hydroxylated boron nitride nanosheet (OH-BNNSs)/water-based polyurethane (WPU)/polyvinyl alcohol (PVA) composite nanofiber membranes with good thermal conductivity. When the content of OH-BNNSs is 10 wt.%, the thermal conductivity of the OH-BNNS/PVA/WPU composite nanofiber membrane can reach 0.629 W (mK)⁻¹, with yield strength, ultimate tensile strength, and elastic modulus of ≈3.85, ≈5.87, and ≈35.22 MPa, respectively. The results indicate that the OH-BNNS/WPU/PVA composite nanofiber membrane exhibits good thermal conductivity and outstanding hydrophilicity. When the content of OH-BNNSs is appropriate, the composite membrane also demonstrates good mechanical properties, showing significant potential in the field of thermally conductive polymer materials.

Front Cover: In article 2400331, Tatsuo Maruyama and co-workers report clickable plastic surfaces with controllable azide surface density by the simple dip-coating method. The surfaces can easily immobilize functional molecules with alkyne groups via strain-promoted azide-alkyne cycloaddition. They succeed in preparing a linear surface gradient of azide group density and also in micropatterning the surfaces by microcontact printing.